1. Field of the Invention
The present invention relates to systems for delivering a dosage of a drug to a patient.
2. Background
Drugs are often intended to be administered to a patient by an at home health care provider. Because of various factors, however, different amounts of the drug must be administered to different patients. Such factors can include, for example, the size and weight of the patient, the age of the patient, the sex of the patient, whether the patient is a child or an adult, etc. Currently, in order to administer the proper dose to the patient, drug delivery devices typically require that the device is manufactured such that the entire volume is metered to deliver the desired dose of the drug, or the at home health care provider must adjust the volume to be delivered, thereby adjusting the dose themselves. Both of these options, however, have certain inherent drawbacks.
In the former case, the manufacturer is required to make several versions of a device, with each version including a different volume (usually incremental) of the drug. Further, because several different versions of the device are required, both the distributor of the drug and the pharmacist are required to use more “shelf space” by keeping an inventory of the various devices containing different amounts of the drug.
In the latter case, it is more likely (as compared to a pharmacist) that the at home health care provider might make an error in setting the proper dosage. This could be especially important if the patient requires an immediate injection of the drug (due to a medical emergency).
A cross section view of an example of a conventional syringe 10 is shown in FIG. 1. The syringe 10 typically comprises a barrel 12 having a proximal end designed for receiving a plunger 18 and a distal end designed for attaching an applicator tip to expel the drug into the patient. Before administration of a medicine, the drug formulation is metered into the barrel 12 of the syringe 10 to a predetermined volume. Next, the plunger 18 is inserted into the proximal end of the barrel 12. The drug can then be expelled by pushing the plunger 18 toward the distal end of the barrel 12.
As shown in FIG. 1, the proximal end of the barrel 12 can further comprise a flange 16, and the distal end of the barrel 12 can further comprise a syringe tip 14. Typically, the plunger 18 further comprises a shaft having a disk-shaped flange 22 located on its proximal end and a stopper 20, usually made of a rubber material, attached to its distal end. The shaft and the disk-shaped flange 22 are often formed from a single piece of material such as either glass or plastic. The stopper 20 is usually attached to the shaft of the plunger 18 by providing a threaded tip (not shown) to the end of the shaft for screwing into the stopper 20.
There is a need for drug delivery systems for the treatment of patients who experience epileptic seizures. Typically, patients who suffer increased and intermittent seizure activity due to epilepsy are treated via a rectal drug delivery device that administers a pre-set dose of a drug such as diazepam in a gel form. As discussed above, however, there is a need for a system that employs a conventional syringe for delivering an adjustable pre-set dosage of a drug.